Automatic pulp grinder control

ABSTRACT

An automatic water shower flow control for a paper pulp grinding machine for control of pulp quality wherein the shower flow is regulated in accordance with the power input to the pulp grinding means.

[451 Dec. 4, 1973 United States Patent [191 Perry [54] AUTOMATIC PULP GRINDER CONTROL 3,693,891 9/1972 Remmer 24l/33 [75] Inventor:

James H. Perry, Worcester, Mass.

[73] Assignee: Norton Company, Worcester, Mass. Primary Examiner-Granville Y. Custer, Jr. [22] Filed: Attorney-Allan R. Redrow July 17, 1972 211 App]. No.: 272,360

[57] ABSTRACT An automatic water shower flow control for a paper pulp grinding machine for control of pulp quality wherein the shower flow is regulated in accordance with the power input to the pulp grinding means.

[52] US. 241/33, 241/282 [51] Int. B02c 23/00 [58] Field of Search 241/28, 33, 36, 41,

[56] References Cited UNITED STATES PATENTS 3,690,568 9/1972 Alexander........................... 241/282 3 Claims, 1 Drawing Figure AUTOMATIC PULP GRINDER CONTROL BACKGROUND OF THE INVENTION Logs are reduced to a fibrous pulp several ways but the most common practice is to subject 2 feet to 6 feet lengths of logs to the action of an abrasive grinding wheel in one of several different types of grinding machines. In such a process, the pieces of logs are pressed against the surface of the pulpstone with their longitudinal axes generally parallel to the axis about which the grinding wheel rotates, while separate shower means direct streams of water onto spaced apart portions on the surface of the wheel to cool and clean the grinding surface and produce a water layer between the grinding surface and the logs. The quantity of water supplied to the grinding operation is quite critical to the production of pulp of the highest quality and most frequently the foreman in charge of the operation manually adjusts certain of the shower control valves from time to time to control the resulting pulp quality.

More recently automated grinding and pulp making operations have been designed for use in conjunction with a computer apparatus designed to integrate a number of control factors in an attempt to produce pulp having a uniform quality. I here provide a much simplified automated control means adapted to vary the critical shower flow to the surface of the pulpstone to obtain direct control of pulp quality in a simple and most expeditious manner.

BRIEF DESCRIPTION OF THE INVENTION In my apparatus [provide an automatic shower control, for example, in a two pocket grinder, that has the usual cleaning and cooling showers which are adapted to be used along with variable flow, quality control showers. The cleaning and cooling showers are positioned to direct a relatively high pressure fluid flow continuously against portions of the moving surface of the grinding wheel as the wheel rotates and the several portions of the wheels surface exit from the respective grinding pockets. The critical quality control shower means are positioned relative to their coacting portions of the pulpstone surface to cause a layer of water to form on the surfaces of the wheel as these grinding surfaces under the influence of these means enter the spaced apart log holding pockets. The volume of water flow to the quality control shower heads is made directly proportional to the infeed power to the grinding wheel and with proper manual adjustment at start-up of the grinding operation, to the type of wood being ground, the abrasive characteristics of the wheel and the grinder pressure being used, control of the pulp quality can be maintained automatically.

DRAWING The drawing diagrammatically shows an end view of a two pocket pulp grinder having a shower system therein which is representative of my invention.

DETAILED DESCRIPTION OF THE INVENTION length which are pressed against opposite sides of the pulpstone by pistons 13 and 14. The pulpstone is driven by a motor 15 that may be one designed to deliver as much as from 10 to 11,000 H.P.

Suitable cleaning and cooling showers 20 and 21 are provided to direct high pressure jets of water against oppositely disposed surfaces of the grinding wheel just as these surface portions leave the grinding pockets. The showers are provided with nozzles to impinge the shower fluid radially inwardly across the entire length of the wheel and against the surface of the pulpstone to loosen and wash away the fibres released from the logs. Additional water may be flushed from showers 20 and 21 onto the surface being cleaned if necessary to cool it to the desired degree whereby to avoid overheating the fibres making up the pulp as the fibres are liberated to mix with the fluid supplied by the quality control showers to produce the pulp. Temperature control at the time of fibre separation and in the pulp mass is critical to production of high quality pulp.

The showers 20 and 21 are supplied with white water from a suitable header 22 that is designed to carry the shower fluid at a minimum of about psi. and in temperature range of about 90 F. to F. The header connects to pipe 23 that has two branch feeder lines 24 and 25 connected to showers 20 and 21 respectively which as above stated function to clean the surface of the pulpstone across its entire length and control its temperature.

All of the apparatus and its operation described so far is conventional and well known to those skilled in the art.

The header 22 also feeds shower water to the quality control showers 30 and 31 of my invention. The connection is through pipe 32 having an automatically controlled throttle valve 33 in it, the valve being positioned to control the volume of fluid delivered to the branch lines 34 and 35 that lead to showers 30 and 31 respectively. These showers direct fluid radially across the entire length of the wheel and against the oppositely disposed surface portions of the pulpstone at locations where these cleaned and cooled surface portions are about to enter the two oppositely disposed grinding pockets. The showers 30 and 31 are the quality control showers that are primarily operative to determine the quality of the resulting pulp. These showers produce a uniform layer of fluid throughout the entire area of the respective surface portions over which they are positioned, which fluid layer is carried at least in part into the grinding zone by being trapped in the pores of the wheel and spaces between the abrasive grits on the surface of the wheel. The primary source of fluid thus made available at the grinding interface between the pulpstone and the wood is controlled by the operation of showers 30 and 31.

As the grinding process continues, depending upon the constant pressure applied by pistons 13 and 14, the kind of wood being ground, the condition of the particular wood, the diameter of the logs and other factors, a fluctuating amount of power is needed to separate the fibres from the logs. The power requirement changes constantly as grinding progresses and I have found, after a proper grinding operation has been started, that a careful control of the quantity of fluid delivered to the showers 30 and 31 can be utilized to maintain the quality of the resulting pulp. As the demand for power to drive the motor 15 goes up the quantity of shower fluid fed to the grinding surface of the pulpstone from showers 30 and 31 should be increased and conversly the fluid flow to the surface from these quality control showers should be diminished as the power to drive motor drops.

In accordance with the preferred form of my invention an electric motor is used to drive the pulpstone and a proportional flow meter is electrically connected to the power lines leading to motor 15. The meter responsive to the energy input to the motor functions to operate a suitable controller means connected to throttle valve 33 whereby the valve is automatically operated in accordance with the meter reading. The meter and controller coact to operate the throttle valve to produce a predetermined flow of fluid to showers 30 and 31 that is automatically adjusted to vary directly with the power fed to motor 15. The specific meter and controller means for valve 33 may be selected from a number of proportional flow control devices sold commercially such as for example an electrical meter and controller that can be purchased from the Leeds and Northrup Company.

Those skilled in the art can initially adjust valve 33 to produce the desired quality of pulp for a given type of wood, as is done in current practice, by manually adjusting valves 36 and 37. This procedure involves loading one pocket 11 for example with wood, pressing the wood against the driven pulpstone while an excess of fluid is showered onto the surface of the grinding wheel at the inlet side of the wheel surface to the pocket from its corresponding quality control shower. The wood is pressed against the wheel until normal grinding action results and then the quality control shower means is manually adjusted by valve 36 to gradually cut off the flow of fluid through the shower. This manual throttling continues until an absence of water permits the wood to get so hot as to produce a burning odor. At this point the manual adjustment of valve 36 is reversed to let more water flow onto the wheel from the quality control shower 30 to an extent to just eliminate the burning odor. This operation is repeated on the other pocket 12 and then when both grinder pockets have been put into operation under the manual control of valves 36 and 37, the flow of fluid to the quality control showers is placed under the control of valve 33. Once the desired quality for the wood being ground has been attained under constant operating conditions, the automatic controller for operating valve 33 can be phased in and as conditions change, the throttle valve 33 is automatically adjusted to supply more or less fluid to the grinding zone depending upon the pre-arranged throttle valve characteristics. In continuous use when the wood in one pocket is all ground up and the pocket must be filled, about 80 percent of the water supply to the respective quality control shower means 30 or 31 for that pocket is cut off by one of the valves 38 and 39 described below. By utilizing a control system and operating throttle valve control means as here disclosed, more constant and sure control of pulp quality can be attained instantaneously and automatically by thus varying the fluid flow from the quality control showers 30 and 31 in previously known proportions, depending upon variations in power input to motor 15.

I have observed the operation of a typical two pocket grinder into which my controller could be built in which the pulpstone was 54 inches long, the shower heads were spaced 4 inches from the surface of the stone, and the showers extend 2 inches beyond each end of the stone to wash the pulp into the pit and to keep the stone and mounting flanges uniformly cooled and clean. The showers sprayed 890 U. S. gallons per minute onto the surface of the stone. This fluid was fed under 100 psi. to the four showers equipped with 78 A inch nozzles. The machine operated under these conditions produced 80 tons per day of pulp having a 1.5 percent consistency.

The actual quantity, composition and temperature of the particular fluid used for quality control, are well known factors that may be varied in order to produce a given quality or type of pulp from a specific kind of wood selected from the various kinds of woods that are made into pulp in conventional pulp grinders. My system provides for automatically controlling the variation of the quantity of the desired fluid flow to showers 30 and 31 within the known parameters of the conventional wood pulp grinding process in accordance with the power utilized in the grinding process.

While I have suggested the use of electrical power measuring means for energizing a suitable controller for the throttle valve, it is apparent that other means may be used. Any means responsive to the torque on the output of the drive motor can be utilized with any suitable sevomotor means to actuate the throttle valve in accordance with my invention.

In normal operation as the pistons 13 and 14 are alternately retracted for loading of their respective pockets, the fluid flow to the quality control shower for the inoperative pocket is cut back by about 80 percent of the flow volume. For this purpose a solenoid operated valve 38 is mounted in line 34 leading to shower 30 and a similar solenoid operated valve 39 is in pipe 35. Valves 38 and 39 are automatically operated to reduce the fluid flow to their associated shower means when a pocket is being loaded. This automatic reduction of fluid to the quality control shower of an inactive pocket prevents the grinding wheel from being unduly cooled by what would otherwise to an over supply of fluid to its surface but yet the residual flow is maintained to prevent over-cooling of the surface of the pulpstone at the inactive area.

The above describes the preferred form of my invention. It is possible that those skilled in the art may design other forms thereof that will fall within the scope of the following claims.

What is claimed is: v

l. A pulpstone grinder for separating fibres from wood comprising a motor for rotating a pulpstone, means to press wood to be ground against a portion of the surface of the pulpstone, a quality control shower means, a source of fluid under pressure to be fed to the shower for delivery by the shower to the portion of the pulpstone surface having an interface with the wood, variable power supply means to drive the motor, a throttle valve between said fluid source and said shower means, and a proportional flow controller means operatively connected between said power supply and said throttle valve and responsive to variations of said power supply to feed more fluid to said interface portion of the pulpstone as the power delivered to the motor increases and to decrease the quantity of fluid feed to the interface when the power delivered to the motor decreases.

2. A grinder like that described in claim 1 wherein the grinder has two wood containing pockets for delivmeans that are operatively positioned to act on oppositely positioned portions of the pulpstone immediately after those portions leave the pockets, and said two separate quality control shower means are positioned closely adjacent to said pockets such that the controlled fluid deposited on the surface portions of the pulpstone is carried immediately into. the interface zones between the wood and pulpstone. 

1. A pulpstone grinder for separating fibres from wood comprising a motor for rotating a pulpstone, means to press wood to be ground against a portion of the surface of the pulpstone, a quality control shower means, a source of fluid under pressure to be fed to the shower for delivery by the shower to the portion of the pulpstone surface having an interface with the wood, variable power supply means to drive the motor, a throttle valve between said fluid source and said shower means, and a proportional flow controller means operatively connected between said power supply and said throttle valve and responsive to variations of said power supply to feed more fluid to said interface portion of the pulpstone as the power delivered to the motor increases and to decrease the quantity of fluid feed to the interface when the power delivered to the motor decreases.
 2. A grinder like that described in claim 1 wherein the grinder has two wood containing pockets for delivery of separate charges of wood to approximately oppositely disposed surfaces of the pulpstone and two separate quality control shower means one each positioned adjacent the oppositely disposed portions of the pulpstone at a point where said potions are about to come in contact with the wood in each one of the respective pockets.
 3. A grinder as described in claim 2 wherein the grinder includes two cleaning and cooling shower means that are operatively positioned to act on oppositely positioned portions of the pulpstone immediately after those portions leave the pockets, and said two separate quality control shower means are positioned closely adjacent to said pockets such that the controlled fluid deposited on the surface portions of the pulpstone is carried immediately into the interface zones between the wood and pulpstone. 